(1) Field of the Invention
The invention relates to a method of barrier layer formation in the fabrication of integrated circuits, and more particularly, to a method of forming a stacked mode tantalum nitride barrier layer to prevent copper diffusion in the manufacture of integrated circuits.
(2) Description of the Prior Art
In a common application for integrated circuit fabrication, a contact/via opening is etched through an insulating layer to an underlying conductive area to which electrical contact is to be made. A barrier layer, typically titanium nitride, is formed within the contact/via opening. A conducting layer material, typically tungsten, is deposited within the contact/via opening. As device sizes continue to shrink, these typical materials are no longer adequate. Because of its lower bulk resistivity, Copper (Cu) metallization is the future technology for feature sizes of 0.18 microns and below. Cu has been used successfully as an interconnection line, but tungsten is still used at the contact level to avoid damage to devices. Cu metallization requires a robust diffusion barrier to prevent the copper from diffusing through the active junctions.
Co-pending U.S. patent application Ser. No. 08/985/404 to S.C. Sun et al, filed on Dec. 5, 1997 discloses a molybdenum nitride barrier for copper metallization. Co-pending U.S. patent applications Ser. No. 09/083,419 to J. B. Lai et al, filed on May 22, 1998 and Ser. No. 09/072/004 to C. S. Lin filed on May 4, 1998 teach a Cu.sub.3 Ge barrier layer for copper metallization. U.S. Pat. No. 5,661,503 to Terai discloses a heat-generating resistor layer of Ta.sub.2 N under a wiring layer such as Al in the fabrication of a liquid jet recording head. U.S. Pat. No. 5,683,928 to Wojnarowski et al and U.S. Pat. No. 5,420,063 to Maghsoudnia et al teach fabricating a thin film resistor using a resistor layer of TaN or Ta.sub.2 N. U.S. Pat. No. 5,676,587 to Landers et al teaches a CMP method for a Ta/TaN/Cu stack. U.S. Pat. No. 5,714,418 to Bai et al teaches a blocking layer, such as TaN or Ta, under a copper layer and a capturing layer, such as Ti, under the blocking layer.